This invention relates to tillage implements and, in particular, to tillage implements utilizing rotary blades.
It is well known that to attain the best agricultural performance from a piece of land, a farmer must cultivate the soil, typically through a tilling operation. Common tilling operations include plowing, harrowing, and sub-soiling. Modem farmers perform these tilling operations by pulling a tilling implement behind a motorized tractor. Depending on the crop selection and the soil conditions, a farmer may need to perform several tilling operations at different times over a crop cycle to properly cultivate the land to suit the crop choice.
In one type of tilling operation, rows or gangs of discs are pulled through soil at depths between 3 and 6 inches to break up clods or lumps of soil, as well as old plant material to provide a more amenable soil structure for planting and to level the soil surface.
The configuration of the tilling implement gangs and their constituent discs will determine the quality and quantity of the passes required to effectively till an area of soil. For example, a gang of parallel flat discs pulled through the soil, each oriented such that their axis of revolution is perpendicular to the direction of pull, will not be very effective at tilling the soil. To improve the tilling action, those skilled in the art have attempted to change the angle at which the gang is oriented. However, an increased gang angle can cause complications. The increased gang angle will leave large clods of soil that may require multiple passes to pulverize. Additionally, the side pressure of the soil against the sides of flat discs or discs having only a shallow concavity of 1.25 to 1.69 inches will often break the discs. To increase disc strength, the disc can be made to be more concave. However, increasing the concavity of the discs to improve their strength promotes the formation of an undesirable compaction layer.
Thus, tilling implements involving discs have a number of drawbacks. First, multiple passes of the tilling implement over the same area of soil may be required to properly cultivate the soil and cut through heavy crop residue. If multiple passes are required, then the farmer will incur increased costs associated with the amount of time and fuel required to prepare the seedbed. Known tilling implements are limited to speeds below approximately 6 miles per hour. Speeds in excess of approximately 6 miles per hour will vertically lift the tilling implement, resulting in the blades engaging the soil by less than 3 to 6 inches. If this occurs, the blades will not effectively till the soil or, if the blades are forced to remain in the soil, it can result in increased disc failure due to the increased pressure applied to the discs by the soil at greater velocities.
Second, existing cultivators compact the soil under the prepared seedbed. This layer of compacted soil inhibits plant germination, root growth, and crop yield. The presence of a compacted layer of soil may require an additional tillage operation such as plowing to break up the compacted earth in order to avoid the problems of poor water absorption and weak anchoring of crops in the ground.
Thus, there is a need for a tilling implement that is capable of thoroughly tilling the soil in a single pass and capable of traveling at greater speeds without excessive disc failure or the formation of a compaction layer.